Since it is considered that erythropoiesis is basically under the control of erythropoietin secretion, it is necessary to have a convenient quantity of this substance disposable for research purposes. It is important as well that it be collected from human beings. Chemical, physiological, inmunological, pharmacological and clinical studies require that erythropoietin be rather obtained from the urine of anemic patients. To organize a laboratory for the collection of erythropoietin in an area where the iron-deficient anemia due to hookworm is endemic, becomes of an absolute importance not only to provide to the N.I.H. with the hormone but also for the study of what is an outstanding public-health problem in the area. The latter is our main objective. To this can be added the development of better extraction and purification methods of the hormone.